A wireless communication device, when initially turned on or when returning from an out of service condition, can perform a scan of radio frequencies to determine a set of potential wireless base stations (or base station equivalents) with which to attempt to associate and/or connect. As is known, the wireless communication device can operate using one or more different radio access technologies in accordance with one or more different wireless communication protocols. Examples of different wireless communication protocols include second-generation wireless telephone technology (2G), third generation of mobile telecommunications technology (3G), fourth generation of mobile telecommunications technology (4G), such as a Long Term Evolution (LTE) wireless communication protocol as published by the Third Generation Partnership Project (3GPP) standardization group, among others.
Wireless communications use predefined frequency ranges, usually referred as bands. The bands are typically formed of a contiguous range of radio frequencies. When a wireless communication device tries to establish a wireless connection, the wireless communication device does band scanning to determine the frequencies on which a base station may be operating. In conventional techniques, the wireless communication device iterates through all known bands until it finds the right one. As signal processing advances and more wireless spectrum is opened up to carriers, there are more and more bands for the wireless communication device to scan. For example, the 4G LTE currently defines more than 40 bands, where each band can have more than 100 channels. In fact, the 3GPP specification allows 65,536 unique channels for LTE communications. As such, scanning can take a long time and consumes a lot of batter power of the wireless communication device, causing slow network attachment and faster battery drain.
To make it worse, carriers have adopted different bands for LTE deployments in different parts of the world (e.g., North America, South America, Europe, Asia-Pacific, and Africa & Middle East). Thus, the operational bands in one region of the world may be different than the operational bands in another region of the world, making scanning more difficult.
One conventional approach to band/channel scanning is to scan from beginning to end of possible bands and channels in sequential order. This approach suffers from the drawback of being extremely inefficient.
Another conventional approach to improve the speed in which a connection is established is to remember recently connected channels, and begin checking those channels first, hoping that the wireless communication device can connect to a previously connected channel again. One shortcoming of this approach is that when a wireless communication device moves from one location to another, the same channel may not be available at the new location. This approach was used successfully when there were only a few channels available worldwide, but is not as effective today due to the large number of possible channels.